Bearings, such as ball bearings, air bearings, and magnetic bearings, are commonly used to permit relative motion of one or more parts in a device. Each type of bearings has its advantages and disadvantages. For example, air bearings provide significantly less friction than ball bearings. Also, the performance of ball bearings is negatively affected by deformities in the shape of the ball bearings. However, in order to properly implement air bearings, it is often necessary to determine the air bearing gap between the air bearing and the moving part. For example, if the device is subject to vibration, knowledge of the air bearing gap distance is necessary to determine if the moving part is contacting the air bearing. If contact occurs, performance of the device will be reduced.
Air bearing gap distances vary based on the application, but the distances can be as small as 1/1000th of an inch (1 mil) or less. Considering that a sheet of paper is around 3-7 mils, the small distances involved make accurate measurements difficult. In addition, current mechanical gauges used to measure the air gap distance have limitations which increase the difficulty in making accurate measurements. For example, current mechanical gauges can only measure one air bearing gap distance at a time. Current mechanical gauges also tend to have hysteresis as the gap distance changes. Hence, a curve plotting changes in gap distances is not smooth but rather has jumps between measured points which limits the ability to measure small changes in gap distance.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an improved system and method for measuring air bearing gap distance.